1. Field of the Invention
The present invention relates to a method of treating or inhibiting the growth of cancerous tumour cells and associated diseases in a mammal by administering an effective amount of a substituted-triazolopyrimidine derivative and pharmaceutically acceptable salts thereof. Further, the present invention relates to a method for the treatment or prevention of (MDR) multiple drug resistance in a mammal in need thereof which method comprises adminstering to said mammal an effective amount of a substituted triazolopyrimidine derivative or a pharmaceutically acceptable salt thereof. More specifically, the present invention relates to a method of treating or inhibiting the growth of cancerous tumour cells and associated diseases in a mammal by interacting with tubulin and microtubules and promotion of microtubule polymerization which comprises administering to said mammal an effective amount of a substituted-triazolopyrimidine derivative and pharmaceutically acceptable salts thereof.
2. Description of the Prior Art
Most of the cytostatics in use today either inhibit the formation of essential precursors for biosynthesis of DNA or block DNA polymerases or interfere with the template function of DNA because DNA was the primary target for developing therapeutic drugs for chemotherapy. Unfortunately, inhibition of the formation of essential precursors for biosynthesis of DNA or blocking DNA polymerases or interference with the template function of DNA also affects normal tissues.
Microtubules are among the cellular structures necessary for cell growth. Tubulin is the biochemical target for several anticancer drugs, which include the vinca alkaloids vincristine and vinblastine. The interaction of vincristine and vinblastine by binding to the alpha and beta-tubulin subunits interfere with the growing and shortening of the microtubules and prevents the formation of microtubules necessary for cell functions. While these compounds have efficacy in cancer chemotherapy, they also have a destabilizing effect on the microtubules which also affects rapidly proliferating normal tissues and leads to toxicity.
Paclitaxel and its semisynthetic derivative docetaxel (Taxotere®) also interfere with microtubule formation and stabilise microtubules. Paclitaxel (Taxol®),is a diterpene isolated from the bark of the Western (Pacific) yew, Taxus brevifolia and is representative of a new class of therapeutic agent having a taxane ring system. It was additionally found in other members of the Taxacae family including the yew of Canada (Taxus canadensis) found in Gaspesia, eastern Canada and Taxus baccata found in Europe whose needles contain paclitaxel and analogs and hence provide a renewable source of paclitaxel and derivatives. The crude extract was tested for the first time during the 1960s and its active principle was isolated in 1971 and the chemical structure identified (M. C. Wani et al, J. Am. Chem. Soc., 93, 2325 (1971)). Further, a wide range of activity over melanoma cells, leukemia, various carcinomas, sarcomas and non-Hodgkin lymphomas as well as a number of solid tumors in animals was shown through additional testing. Paclitaxel and its analogs have been produced by partial synthesis from 10-deacetylbaccatin III, a precursor obtained from yew needles and twigs, and by total synthesis (Holton, et al., J. Am. Chem. Soc. 116:1597-1601 (1994) and Nicolaou, et al., Nature 367:630-634 (1994)). Paclitaxel has been demonstrated to possess antineoplastic activity. More recently, it was shown that the antitumor activity of paclitaxel is due to a promotion of microtubule polymerization (Kumar, N., J. Biol. Chem. 256:10435-10441 (1981); Rowinsky, et al., J. Natl. Cancer Inst., 82:1247-1259 (1990); and Schiff, et al., Nature, 277:665-667 (1979)). Paclitaxel has now demonstrated efficacy in several human tumors in clinical trials (McGuire, et al., Ann. Int. Med., 111:273-279 (1989); Holmes, et al., J. Natl. Cancer Inst., 83:1797-1805 (1991); Kohn et al., J. Natl. Cancer Inst., 86:18-24 (1994); and A. Bicker et al., Anti-Cancer Drugs, 4,141-148 (1993)
Paclitaxel is a microtubule blocker, inhibiting mitosis by interaction with microtubules. Paclitaxel does not prevent tubulin assembly but rather accelerates tubulin polymerization and stabilizes the assembled microtubules. Paclitaxel acts in a unique way which consists in binding to microtubules, preventing their depolymerization under conditions where usually depolymerization occurred(dilution, calcium, cold and microtubules disrupting drugs). Paclitaxel blocks the cell cycle at prophase which results in an accumulation of cells in G2+M.
Accordingly, there is still a need in the art for cytotoxic agents for use in cancer therapy. In particular, there is a need for drugs which inhibit or treat the growth of tumors which have an effect similar to paclitaxel and interfere with the process of microtubule formation. Additionally, there is a need in the art for agents which accelerate tubulin polymerization and stabilize the assembled microtubules.
Accordingly, it would be advantageous to provide a method of treating or inhibiting cell proliferation, neoplastic growth and malignant tumor growth in mammals by administering compounds which have paclitaxel like anticancer activity.
Additionally, it would be advantageous to provide a method for treating or inhibiting multiple drug resistance (MDR).
Substituted triazolopyrimidine compounds of this invention are known to the art and have found use in agriculture as fungicides. The preparation of compounds of this invention and methods of preparation are disclosed in the following U.S. Pat. Nos.: 5,593,996; 5,756,509; 5,948,783; 5,981,534; 5,612,345; 5,994,360; 6,020,338; 5,985,883; 5,854,252; 5,808,066; 5,817,663; 5,955,252; 5,965,561; 5,986,135; and 5,750,766.
Compounds of this invention are also prepared according to procedures described in the following International Publication Numbers: WO98/46607; WO98/46608; WO99/48893; WO99/41255; EPO 834513A2; EPO 782997A2; EPO 550113B1; EPO 613900B1; FR2784381A1; EPO 989130A1; WO98/41496; WO94/20501; EPO 945453A1; EPO 562615A1 and EPO 562615B1.